Police patrolling the red-light district of the Belgian capital have been ordered to stop visiting brothels and drinking in bars when on duty.

A letter sent to officers in Brussels' northern police district, and published in a Belgian daily Tuesday, urged them to set a good example and earn the public's respect.

"These officers think their duty hours are to be used to drink alcohol in bars, practice sports..., visit brothels or massage parlors, and entertain (intimate) relationships with residents of the neighborhood during their patrol," said the letter from a local police chief.

"It is only by setting a good example that the police can make itself respected," the letter said, urging officers to adopt more conservative behavior.

A police spokesman confirmed the letter was authentic, but said the police chief had only reacted to rumors of officers behaving badly while on duty.

"There was no concrete evidence to substantiate any wrongdoing by police officers ... If there had been, they would have been prosecuted," said spokesman Roland Thiebauld.